The yawning gap in neuroscientists’ understanding of their topic is in the intermediate scale of the brain’s anatomy. Science has a passable knowledge of how individual nerve cells, known as neurons, work. It also knows which visible lobes and ganglia of the brain do what. But how the neurons are organised in these lobes and ganglia remains obscure.

(sociology) Able to "pass", or be accepted as a member of a race, sex or other group to which society would not otherwise regard one as belonging.

2014, Paul Stryker, Confessions of a Sex Offender (page 33)

The idea of something, or someone, being unusual and sexual is intoxicating. I concluded that if I ever met a very passable transsexual and we were attracted to one another, I'd go bisexual and pursue the relationship.